The present invention relates generally to check valves, and particularly to mechanical prosthetic heart valves for human implantation.
Various prosthetic heart valves have been developed to replace diseased or defective human heart valves. These designs have included single leaflet valves such as that disclosed in U.S. Pat. No. 3,445,863 issued to Wada, U.S. Pat. No. 3,835,475 issued to Child, and U.S. Pat. No. 3,824,629 issued to Shiley.
Alternative designs employ two generally flat, semicircular leaflets mounted within a circular valve housing. Some such designs as disclosed in U.S. Pat. No. 4,373,216 issued to Klawitter and U.S. Pat. No. 4,276,658 issued to Hansen employ generally flat leaflets having pivot axes close to the center line of the valve and leaflets which move toward the center of the valve during opening. Other such designs have employed leaflets having pivot axes substantially displaced from the center of the valve which open away from the center of the valve and allow for more centralized blood flow. Such a design is illustrated in U.S. Pat. Re. 31,040 issued to Possis.
A third group of designs employs leaflets having conical or cylindrical surfaces, pivot axes adjacent to or somewhat displaced from the center of the valve and leaflets which open away from the center of the valve to provide for central blood flow. Such designs are disclosed in U.S. Pat. Nos. 4,363,142 issued to Meyer, No. 4,274,437 issued to Watts, and No. 4,488,318 issued to Kaster, and in U.S. Pat. No. 4,476,789 issued to Sorensen and Woien, filed May 16, 1985.